ᐅ Underfloor heating with an air-to-water heat pump. House gets too warm when the sun is shining.

Created on: 4 Dec 2019 14:18
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chewbacca123
Hello everyone,

I have a general question.

We moved into our new build four months ago. The living area on the ground floor has three large floor-to-ceiling windows facing south. We have underfloor heating and an air-to-water heat pump.
It provides a really comfortable temperature inside the house, but we have a problem – whenever the sun is shining in winter, even if it’s -2°C (28°F) outside, the temperature suddenly rises to 24°C (75°F) in the living room. It gets uncomfortably warm in here, and the underfloor heating can’t be turned down quickly.
Should we assume that the large floor-to-ceiling windows are responsible for the heat gain? A photo of the south-facing side of the house is attached.
What would you do – always lower all the blinds as soon as sunlight is forecast? That seems quite annoying...
We have motorized blinds controlled by Somfy. Would you consider buying a sensor that automatically lowers the blinds at a certain temperature?

Thanks in advance for your replies.

Neues zweistöckiges Haus auf Baustelle mit weißer Blockfassade, pinker Dämmung und großen Fenstern
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Bookstar
6 Dec 2019 16:20
My endpoint is 28 degrees Celsius (82°F), which is sufficient.
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guckuck2
6 Dec 2019 16:22
Bookstar schrieb:

My end point is 28 degrees, which is enough.

Return flow, yes. Supply flow would be quite optimistic. But we will only find out when it actually gets really cold.
chewbacca1236 Dec 2019 17:03
Lumpi_LE schrieb:

The heating curve looks quite normal, it’s very strange that it’s showing you any supply temperatures of 65°C (149°F)...

I just discovered this:

HVAC heating display with temperatures: supply, return, outside temperature, average temperature
chewbacca1236 Dec 2019 17:05
Bookstar schrieb:

My endpoint is 28 degrees, which is sufficient.
I just found this, which is probably the actual value:

Thermostat display shows supply temperature 30.9°C (87.6°F), return temperature 30.7°C (87.3°F), and outside temperature 2.8°C (37.0°F).
Climbee6 Dec 2019 17:24
chewbacca, didn't someone here write that they spent a few hours thoroughly studying the user manual to optimize their heating system settings?
I think you won't be able to avoid that either.
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guckuck2
6 Dec 2019 17:37
30.9°C (88°F) at an outside temperature of 3°C (37°F) is far too high. The return temperature is only 0.2 K below the supply temperature, meaning the heating energy remains in the water. Most likely, all ERRs are closed?!

I would recommend having the system inspected. Nothing is working properly.